Objective: We aimed to assess the association between the alleles of vitamin D receptor (VDR) gene polymorphisms and Graves' disease (GD) through systematic reviews and meta-analyses of the literature.
Design: We searched the electronic databases of MEDLINE, EMBASE and HuGeNet (up to April 2008), in combination with manual bibliographical searches. Meta-analyses of all the eligible studies were performed, which focused on four most commonly investigated VDR polymorphisms, ApaI, BsmI, TaqI and FokI.
Patients: A total of 1820 GD patients and 2066 controls from Caucasian and Asian populations were included in the meta-analyses.
Measurements: The odds ratio (OR) was used as the measure of effect size. We performed analyses by estimating the race-specific ORs. Sensitivity analyses were performed by excluding studies with controls inconsistent with Hardy-Weinberg equilibrium.
Results: The pooled ORs for ApaI, BsmI and FokI in Asian populations were 1.31 (95% CI: 1.04-1.66, P = 0.02), 1.58 (95% CI: 1.13-2.22, P = 0.007) and 1.68 (95% CI: 1.28-2.20, P = 0.0002), respectively. None of the four polymorphisms had a statistically significant association between VDR variants and susceptibility to GD in Caucasian populations. Sensitivity analyses generated similar results to those of the primary analyses.
Conclusion: The evidence accumulated suggested that ApaI, BsmI and FokI polymorphisms in the VDR gene were associated with susceptibility to GD in Asian populations, while ApaI, BsmI, TaqI and FokI polymorphisms were not associated with GD in Caucasian populations. Additional studies are required to allow a more definitive conclusion.